U.S. patent application number 16/781020 was filed with the patent office on 2020-08-13 for valve timing adjustment device, and control device and control method for valve timing adjustment device.
The applicant listed for this patent is DENSO CORPORATION. Invention is credited to Kenji TADA, Hiroki TAKAHASHI.
Application Number | 20200256219 16/781020 |
Document ID | 20200256219 / US20200256219 |
Family ID | 1000004674784 |
Filed Date | 2020-08-13 |
Patent Application | download [pdf] |
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United States Patent
Application |
20200256219 |
Kind Code |
A1 |
TAKAHASHI; Hiroki ; et
al. |
August 13, 2020 |
VALVE TIMING ADJUSTMENT DEVICE, AND CONTROL DEVICE AND CONTROL
METHOD FOR VALVE TIMING ADJUSTMENT DEVICE
Abstract
A valve timing adjustment device having a phase adjustment unit
including an input rotator, a driving rotator that rotates in
conjunction with a crankshaft, a driven rotator that rotates in
conjunction with a camshaft that changes a relative rotation phase
between the driving rotator and the driven rotator. A controller is
configured to perform a startup phase control when operation of the
internal combustion engine is started, the startup phase control
including setting the relative rotation phase to a predetermined
initial phase, and perform a startup preparation control during a
period after the internal combustion engine is stopped and before
the startup phase control is performed, the startup preparation
control including changing the relative rotation phase.
Inventors: |
TAKAHASHI; Hiroki;
(Kariya-city, JP) ; TADA; Kenji; (Kariya-city,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DENSO CORPORATION |
Kariya-city |
|
JP |
|
|
Family ID: |
1000004674784 |
Appl. No.: |
16/781020 |
Filed: |
February 4, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02D 13/0219 20130101;
F01L 2800/01 20130101; F01L 2201/00 20130101; F01L 1/344
20130101 |
International
Class: |
F01L 1/344 20060101
F01L001/344; F02D 13/02 20060101 F02D013/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 12, 2019 |
JP |
2019-022297 |
Claims
1. A valve timing adjustment device for an internal combustion
engine that adjusts opening and closing timings of a valve which is
opened and closed by a camshaft driven by torque transmitted from a
crankshaft, the valve timing adjustment device comprising: a phase
adjustment unit including an input rotator, a driving rotator that
rotates in conjunction with the crankshaft, a driven rotator that
rotates in conjunction with the camshaft, and a speed reduction
mechanism that connects each of the driving rotator and the driven
rotator to the input rotator so as to be rotatable relative to the
input rotator, the speed reduction mechanism being configured to
change a relative rotation phase between the driving rotator and
the driven rotator in accordance with a rotation of the input
rotator; an actuator configured to rotate the input rotator; and a
controller that controls rotation of the actuator to control the
relative rotation phase, wherein the controller is configured to
perform a startup phase control when operation of the internal
combustion engine is started, the startup phase control including
setting the relative rotation phase to a predetermined initial
phase, and perform a startup preparation control during a period
after the internal combustion engine is stopped and before the
startup phase control is performed, the startup preparation control
including changing the relative rotation phase.
2. The valve timing adjustment device according to claim 1, wherein
the startup preparation control is performed after a command to
start the internal combustion is received and before a cranking
operation of the internal combustion engine is started.
3. The valve timing adjustment device according to claim 1, wherein
the startup preparation control is performed during a cranking
operation of the internal combustion engine after a command to
start the internal combustion is received.
4. The valve timing adjustment device according to claim 2, further
comprising: a temperature detection unit that detects a temperature
of the valve timing adjustment device, wherein the controller is
configured to perform the startup preparation control when a
detected temperature detected by the temperature detection unit is
lower than a predetermined temperature.
5. The valve timing adjustment device according to claim 1, wherein
the startup preparation control is performed during a period after
the internal combustion is stopped and before a command to start
the internal combustion engine is received.
6. The valve timing adjustment device according to claim 1, wherein
the startup preparation control includes an advance angle operation
that advances the relative rotation phase and a retard angle
operation that retards the relative rotation phase.
7. The valve timing adjustment device according to claim 6, wherein
the startup preparation control includes alternately performing the
advance angle operation followed by the retard angle operation a
plurality of times, or repeatedly performing the retard angle
operation followed by the advance angle operation a plurality of
times.
8. The valve timing adjustment device according to claim 1, wherein
the speed reduction mechanism includes a planetary gear that
performs planetary motion in response to the rotation the input
rotator, and the startup preparation control includes operating the
planetary gear at perform at least one full revolution.
9. The valve timing adjustment device according to claim 1, wherein
the speed reduction mechanism is a roller mechanism including a
plurality of rollers configured to rotate to reduce the rotation
speed of the input rotator.
10. A control device for a valve timing adjustment device of an
internal combustion engine that adjusts opening and closing timings
of a valve which is opened and closed by a camshaft driven by
torque transmitted from a crankshaft, the valve timing adjustment
device including a phase adjustment unit including an input
rotator, a driving rotator that rotates in conjunction with the
crankshaft, a driven rotator that rotates in conjunction with the
camshaft, and a speed reduction mechanism that connects each of the
driving rotator and the driven rotator to the input rotator so as
to be rotatable relative to the input rotator, the speed reduction
mechanism being configured to change a relative rotation phase
between the driving rotator and the driven rotator in accordance
with a rotation of the input rotator, and an actuator configured to
rotate the input rotator, wherein the control device is configured
to perform a startup phase control when operation of the internal
combustion engine is started, the startup phase control including
controlling the relative rotation phase to a predetermined initial
phase, and perform a startup preparation control during a period
after the internal combustion engine is stopped and before the
startup phase control being performed, the startup preparation
control including changing the relative rotation phase.
11. A control method of a valve timing adjustment device for an
internal combustion engine that adjusts opening and closing timings
of a valve which is opened and closed by a camshaft driven by
torque transmitted from a crankshaft, the method comprising:
performing a startup phase control when operation of the internal
combustion engine is started, the startup phase control including
setting a relative rotation phase to a predetermined initial phase,
the relative rotation phase being between a driving rotator that
rotates in conjunction with the crankshaft and a driven rotator
that rotates in conjunction with the camshaft; and performing a
startup preparation control during a period after the internal
combustion engine is stopped and before the startup phase control
being performed, the startup preparation control including changing
the relative rotation phase.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a valve timing adjustment
device.
BACKGROUND
[0002] An internal combustion engine may include a valve timing
adjustment device that adjusts the rotation phase of a camshaft
relative to a crankshaft to adjust the opening and closing timings
of a valve.
SUMMARY
[0003] In one aspect, a valve timing adjustment device for an
internal combustion engine that adjusts opening and closing timings
of a valve which is opened and closed by a camshaft driven by
torque transmitted from a crankshaft is proposed. The valve timing
adjustment device of this embodiment includes a phase adjustment
unit including an input rotator, a driving rotator that rotates in
conjunction with the crankshaft, a driven rotator that rotates in
conjunction with the camshaft, and a speed reduction mechanism that
connects each of the driving rotator and the driven rotator to the
input rotator so as to be rotatable relative to the input rotator,
the speed reduction mechanism being configured to change a relative
rotation phase between the driving rotator and the driven rotator
in accordance with a rotation of the input rotator, an actuator
configured to rotate the input rotator, and a controller that
controls rotation of the actuator to control the relative rotation
phase. The controller is configured to perform a startup phase
control when operation of the internal combustion engine is
started, the startup phase control including setting the relative
rotation phase to a predetermined initial phase, and perform a
startup preparation control during a period after the internal
combustion engine is stopped and before the startup phase control
is performed, the startup preparation control including changing
the relative rotation phase.
BRIEF DESCRIPTION OF DRAWINGS
[0004] FIG. 1 is a schematic cross-sectional view showing a
configuration of a valve timing adjustment device according to a
first embodiment.
[0005] FIG. 2 is a schematic cross-sectional view of the valve
timing adjustment device taken along line 2-2 shown in FIG. 1.
[0006] FIG. 3 is a schematic cross-sectional view of a phase
adjustment unit taken along line 3-3 shown in FIG. 1.
[0007] FIG. 4 is a schematic cross-sectional view of a driving
rotator and a driven rotator taken along line 4-4 shown in FIG.
1.
[0008] FIG. 5 is an explanatory diagram showing a flowchart of a
startup processing according to the first embodiment.
[0009] FIG. 6 is an explanatory diagram showing an example of a
timing chart when the startup processing of the first embodiment is
executed.
[0010] FIG. 7 is an explanatory diagram showing a flowchart of a
startup processing according to a second embodiment.
[0011] FIG. 8 is an explanatory diagram showing an example of a
timing chart when the startup processing of the second embodiment
is executed.
[0012] FIG. 9 is an explanatory diagram showing a flowchart of a
stop processing according to a third embodiment.
[0013] FIG. 10 is an explanatory diagram showing an example of a
timing chart when the stop processing of the third embodiment is
executed.
[0014] FIG. 11 is a schematic cross-sectional view showing a
configuration of a valve timing adjustment device according to a
fourth embodiment.
[0015] FIG. 12 is a schematic cross-sectional view of a phase
adjustment unit taken along line 12-12 shown in FIG. 11.
[0016] FIG. 13 is a schematic cross-sectional view of a phase
adjustment unit taken along line 13-13 shown in FIG. 11.
DETAILED DESCRIPTION
1. First Embodiment
[0017] Referring to FIG. 1, a valve timing adjustment device 10 of
a first embodiment is applied to an internal combustion engine 500
that generates a driving force for a vehicle. In the internal
combustion engine 500, an intake valve (not shown) is opened and
closed by the rotation of a camshaft 510. The camshaft 510 rotates
when torque is transmitted from a crankshaft 520. In other words,
the camshaft 510 is a driven shaft and the crankshaft 520 is a
driving shaft. The valve timing adjustment device 10 is connected
to the camshaft 510 and the crankshaft 520. During the operation of
the internal combustion engine 500, the valve timing adjustment
device 10 adjusts the opening and closing timing of the valve by
changing the rotation phase of the camshaft 510 with respect to the
rotation phase of the crankshaft 520. Here, in the present
specification, the phrase "operation of the internal combustion
engine 500" refers to continuous combustion in a combustion chamber
of the internal combustion engine 500 to generate torque.
[0018] The valve timing adjustment device 10 includes a controller
11 that is a hardware control device, an actuator 12 that is a
source of driving force, and a phase adjustment unit 15 that is a
gear unit. The controller 11 is a microcontroller including a
processor and a storage device, e.g., a memory have computer
programs stored thereon that when executed by the processor cause
the processor to perform various functions described herein. The
controller 11 controls the operation of the valve timing adjustment
device 10 in accordance with commands from an ECU (Electronic
Control Unit) 550 that controls the operation of the internal
combustion engine 500.
[0019] During the operation of the internal combustion engine 500,
the controller 11 controls the operation of the actuator 12 to
control a relative rotation phase which is described later. As a
result, the valve timing adjustment device 10 is able to control
the operation of adjusting the opening and closing timing of the
intake valve. In the first embodiment, when starting the operation
of the internal combustion engine 500, the controller 11 executes a
startup processing which includes a startup preparation control and
a startup phase control. The startup processing, the startup
preparation control, and the startup phase control will be
described later. It should be noted that at least some of the
functions of the controller 11 may be implemented as a hardware
circuit, i.e., logic circuitry. Further alternatively, the
controller 11 may be implemented as a part of the ECU 550.
[0020] The actuator 12 is a device that generates a driving force
for changing the rotation phase of the camshaft 510 relative to the
crankshaft 520. The actuator 12 may be a DC brushless motor, for
example. The actuator 12 is housed in a casing 12c. The actuator 12
includes a main body 12M that generates a rotational driving force.
The main body 12M includes an electromagnetic coil, a stator, and a
rotor. The actuator 12 also includes a driving rotating shaft 13
connected to the rotor. In the first embodiment, the actuator 12 is
configured such that only the driving rotating shaft 13, which
transmits torque, is connected to the phase adjustment unit 15.
Meanwhile, the main body 12M is disposed at a position separate
from the phase adjustment unit 15.
[0021] The driving rotating shaft 13 is supported by the casing 12c
so as to be rotatable forward and backward. The driving rotating
shaft 13 is connected to the phase adjustment unit 15 at a tip
portion of the driving rotating shaft 13 that protrudes from the
casing 12c. The central axis of the driving rotating shaft 13
coincides with a rotation axis AX of the camshaft 510. The actuator
12 further includes an energization control unit (not shown)
provided in the casing 12c. The energization control unit includes
components such as a drive unit and a microcontroller for
controlling the drive unit. The energization control unit is under
the command of the controller 11 and controls the energization of
the stator in the actuator 12 to control the rotation of the
driving rotating shaft 13.
[0022] The phase adjustment unit 15 is a device that changes the
rotation phase of the camshaft 510 with respect to the crankshaft
520 using the driving force of the actuator 12. The phase
adjustment unit 15 includes an input rotator 20 connected to the
actuator 12, a driving rotator 30 that rotates in conjunction with
the crankshaft 520, and a driven rotator 40 that rotates in
conjunction with the camshaft 510. The phase adjustment unit 15
further includes a reduction mechanism 50 that reduces the rotation
speed from the input rotator 20.
[0023] Next, referring to FIGS. 1 and 2, the input rotator 20 has a
substantially cylindrical shape, and the driving rotating shaft 13
of the actuator 12 is inserted in the input rotator 20. The driving
rotating shaft 13 is connected to the inner peripheral wall surface
of the input rotator 20 via a connecting member 22 fitted to the
outer periphery of the driving rotating shaft 13. As a result, the
input rotator 20 rotates together with the driving rotating shaft
13 of the actuator 12.
[0024] Next, referring to FIGS. 1 and 3, in the first embodiment,
the input rotator 20 includes an eccentric portion 23. In addition,
the speed reduction mechanism 50 includes a planetary gear 52. The
eccentric portion 23 engages the planetary gear 52 to cause a
revolving (orbital) motion in the planetary gear 52. The center
axis of the eccentric portion 23 is an eccentric axis BX. The
eccentric axis BX is offset to one side in a radial direction with
respect to the rotation axis AX. Here, the radial direction is
perpendicular to the rotation axis AX. The eccentric portion 23
includes a pair of recessed portions that are arranged along the
circumferential direction around the rotation axis AX. This pair of
recessed portions open outward in the radial direction. Each
recessed portion houses an elastic member 24 that generates a
restoring force. The elastic members 24 may be, for example, a
metal leaf spring with a substantially U-shaped cross section. The
planetary gear 52 is biased by the elastic members 24 of the
eccentric portion 23 toward the driving rotator 30 and the driven
rotator 40.
[0025] Next, referring to FIGS. 1 and 2, the driving rotator 30 has
a substantially cylindrical shape and forms the outermost
peripheral portion of the phase adjustment unit 15. As such, the
input rotator 20, the driven rotator 40, and the speed reduction
mechanism 50 are all accommodated within the driving rotator 30.
The driving rotator 30 includes a first member 31 disposed closer
toward the actuator 12 and a second member 32 disposed closer
toward the camshaft 510. The driving rotator 30 is configured such
that the first member 31 and the second member 32 are integrally
fastened together by a plurality of bolts BT. The input rotator 20
is supported via a bearing 33 so as to be rotatable about the
rotation axis AX inside the first member 31.
[0026] A sprocket 35 is formed on the outer periphery of the second
member 32. The driving rotator 30 and the crankshaft 520 are
connected together by an annular endless timing chain 521 that
extends between the sprocket 35 and the crankshaft 520. In FIG. 1,
for convenience, the timing chain 521 is illustrated by a two-dot
chain line. In the internal combustion engine 500, the torque of
the crankshaft 520 is transmitted to the sprocket 35 through the
timing chain 521, and the driving rotator 30 rotates in conjunction
with the crankshaft 520. Further, although detailed descriptions
and illustrations are omitted, the driving rotator 30 includes a
signal plate that is a disk-like member. This signal plate allows
the controller 11 to detect the rotation angle of the driving
rotator 30. The signal plate is attached to the driving rotator 30
such that the signal plate is rotatable together with the driving
rotator 30.
[0027] Referring to FIG. 1, the driven rotator 40 has a cylindrical
shape with a bottom and is accommodated inside the second member
32. The driven rotator 40 is arranged in the second member 32 such
that the central axis of the driven rotator 40 coincides with the
rotation axis AX of the camshaft 510. In addition, the driven
rotator 40 is disposed to open toward the first member 31 of the
driving rotator 30. The driven rotator 40 is assembled so as to be
rotatable relative to the driving rotator 30 about the rotation
axis AX. The driven rotator 40 is fixed to the end of the camshaft
510 by a center bolt CB passing through a bottom wall portion
facing the camshaft 510. Here, the term "bottom wall" refers to the
end face portion of the cylindrical shape of the driven rotator 40,
rather than referring to wall portions in the top/bottom direction.
As a result, the driven rotator 40 rotates in conjunction with the
camshaft 510.
[0028] Referring to FIG. 4, a plurality of engaging portions 36 are
arranged at equal intervals on the inner peripheral surface of the
second member 32 of the driving rotator 30. The plurality of
engaging portions 36 are inward teeth protruding radially toward
the outer peripheral surface of the driven rotator 40. As one
example, four such engaging portions 36 may be provided. In
addition, a plurality of engaged portions 42 are arranged at equal
intervals on the outer peripheral surface of the driven rotator 40.
The plurality of engaged portions 42 are outward teeth protruding
in the radial direction toward the inner peripheral surface of the
second member 32 of the driving rotator 30. The plurality of
engaged portions 42 are arranged such that each engaged portion 42
is interposed between adjacent ones of the engaging portions 36 of
the driving rotator 30. As one example, four such engaged portions
42 may be provided.
[0029] When the engaging portion 36 of the driving rotator 30 and
the engaged portion 42 of the driven rotator 40 are not in contact
with each other, relative rotation between the driving rotator 30
and the driven rotator 40 is allowed. Conversely, when the engaging
portion 36 of the driving rotator 30 and the engaged portion 42 of
the driven rotator 40 are in contact with each other, relative
rotation between the driving rotator 30 and the driven rotator 40
is restricted. As a result, the driving rotator 30 and the driven
rotator 40 rotate together. In the phase adjustment unit 15, a
most-retarded angle and a most-advanced angle of the relative
rotation phase between the driving rotator 30 and the driven
rotator 40 are defined by the arrangement pitch of the engaging
portions 36 and the engaged portions 42. It should be noted that
the relative rotation phase between the driving rotator 30 and the
driven rotator 40 is also the relative rotation phase between the
crankshaft 520 and the camshaft 510.
[0030] Next, referring to FIGS. 1 and 2, the speed reduction
mechanism 50 connects the driving rotator 30 and the driven rotator
40 so as to be rotatable relative to the input rotator 20. The
speed reduction mechanism 50 is configured to change the relative
rotation phase between the driving rotator 30 and the driven
rotator 40 in accordance with the rotation of the input rotator 20.
In the first embodiment, the speed reduction mechanism 50 is a 2K-H
type planetary gear mechanism. The speed reduction mechanism 50
includes the eccentric portion 23 provided in the input rotator 20
that functions as an input shaft, a driving-side inward gear
portion 37 provided in the driving rotator 30, a driven-side inward
gear portion 43 provided in the driven rotator 40, a planetary
bearing 51, and a planetary gear 52.
[0031] Next, referring to FIGS. 1 and 2, the drive side inward gear
portion 37 is provided on the inner peripheral side wall surface of
the first member 31. The central axis of the drive side inward gear
portion 37 coincides with the rotation axis AX of the camshaft 510.
The driven side inward gear portion 43 is provided on the inner
wall of the driven rotator 40. Specifically, referring to FIG. 1,
the driven side inward gear portion 43 is provided on the inner
peripheral side wall surface of the driven rotator 40. The central
axis of the driven side inward gear portion 43 coincides with the
rotation axis AX of the camshaft 510. The diameter of the driven
side inward gear portion 43 is set to be smaller than the diameter
of the drive side inward gear portion 37. Further, the number of
teeth of the driven side inward gear portion 43 is set to be
smaller than the number of teeth of the drive side inward gear
portion 37.
[0032] As shown in FIG. 3, the planetary bearing 51 surrounds the
outer periphery of the input rotator 20. The planetary bearing 51
is disposed outward of the eccentric portion 23 of the input
rotator 20 with a predetermined clearance. The planetary bearing 51
transmits the force received from each elastic member 24 of the
eccentric portion 23 to the planetary gear 52.
[0033] As shown in FIGS. 1 and 3, the planetary gear 52 has a
stepped cylindrical shape. The planetary gear 52 includes a large
diameter portion 52a closer toward the actuator 12 and a small
diameter portion 52b closer toward the camshaft 510 with respect to
the axial direction. The diameter of the large diameter portion 52a
is larger than that of the small diameter portion 52b. As shown in
FIG. 3, the large diameter portion 52a of the planetary gear 52
include a driving-side outward gear portion 53 in which outward
facing teeth are arranged to mesh with the driving-side inward gear
portion 37 provided in the driving rotator 30. The small-diameter
portion 52b of the planetary gear 52 has a driven-side outward gear
portion 54 in which outward facing teeth are arranged to mesh with
the driven-side inward gear portion 43 provided on the driven
rotator 40. When the input rotator 20 rotates about the rotation
axis AX, the planetary gear 52 performs a planetary motion that
revolves around the rotation axis AX while rotating about the
eccentric axis BX. At this time, the rotation speed of the
planetary gear 52 is reduced with respect to the rotation speed of
the input rotator 20.
[0034] Next, the phase adjustment unit 15 changing the relative
rotation phase caused by controlling the actuator 12 will be
described. When the controller 11 controls the driving rotating
shaft 13 of the actuator 12 to rotate at the same speed as the
driving rotator 30 and does not control the input rotator 20 to
rotate relative to the driving rotator 30, the planetary gear 52 is
driven without planetary motion. As a result, the driving rotator
30 and the driven rotator 40 are rotated together. Therefore, the
relative rotation phase between the driving rotator 30 and the
driven rotator 40 is maintained at a constant value without
change.
[0035] In contrast, when the controller 11 controls the driving
rotating shaft 13 of the actuator 12 to rotate at a lower speed or
rotate in reverse with respect to the driving rotator 30 and
controls the input rotator 20 to rotate relative to the driving
rotator 30 in the retard direction, the planetary gear 52 moves in
a planetary motion. As a result, the driven rotator 40 rotates
relative to the driving rotator 30 in the retard direction.
Therefore, the relative rotation phase between the driving rotator
30 and the driven rotator 40 changes to the retard side.
[0036] Further, when the controller 11 controls the driving
rotating shaft 13 of the actuator 12 to rotate at a higher speed
with respect to the driving rotator 30 and controls the input
rotator 20 to rotate relative to the driving rotator 30 in the
advance direction, the planetary gear 52 moves in a planetary
motion. As a result, the driven rotator 40 rotates relative to the
driving rotator 30 in the advance direction. Therefore, the
relative rotation phase between the driving rotator 30 and the
driven rotator 40 changes to the advance side.
[0037] Referring to FIG. 1, during operation of the internal
combustion engine 500, the phase adjustment unit 15 of the valve
timing adjustment device 10 is filled with lubricating oil for
facilitating the operation of the various elements 20, 30, 40, and
50. When the operation of the internal combustion engine 500 is
started, the lubricating oil is supplied to the phase adjustment
unit 15 by a pump 530 that is driven under the control of the ECU
550. This lubricating oil is supplied through a supply path 512
provided in the camshaft 510 and fills the internal space of the
driving rotator 30 in which the input rotator 20, the driven
rotator 40 and the speed reduction mechanism 50 are accommodated.
As the various rotating elements in the phase adjustment unit 15
rotates, the lubricating oil in the phase adjustment unit 15 is
discharged to outside through a discharge path (not shown) provided
in the phase adjustment unit 15. The discharged lubricating oil is
stored in an oil pan (not shown). Then, by operating the pump 530,
the lubricating oil is recirculated into the phase adjustment unit
15 through the supply path 512. Since the pump 530 is stopped after
the operation of the internal combustion engine 500 is stopped, the
operation of the phase adjustment unit 15 is stopped while the
phase adjustment unit 15 is filled with the lubricating oil.
[0038] In addition, the valve timing adjustment device 10 includes
a temperature detection unit 540 that detects the temperature of
the valve timing adjustment device 10. The temperature detection
unit 540 may be a temperature sensor, for example. The temperature
detection unit 540 is installed on the outside of the valve timing
adjustment device 10. Alternatively, the temperature detection unit
540 may be installed at a position exposed to the lubricating oil
inside the valve timing adjustment device 10. Further
alternatively, the temperature detection unit 540 may detect the
temperature of a refrigerant after the refrigerant has exchanged
heat with the valve timing adjustment device 10. The controller 11
uses the detection result of the temperature detection part 540 in
the startup processing explained below.
[0039] With reference to the flowchart of FIG. 5 and the timing
chart of FIG. 6, the startup processing of the first embodiment
executed by the valve timing adjustment device 10 will be
described. This startup processing is performed when the operation
of the internal combustion engine 500 is started up. The upper
section of FIG. 6 shows change over time in the relative rotation
phase between the driving rotator 30 linked to the crankshaft 520
and the driven rotator 40 linked to the camshaft 510. The lower
section of FIG. 6 shows change over time in the rotation speed of
the internal combustion engine 500. In FIG. 6, a value of 0 for the
relative rotation phase is defined as when the relative rotation
phase is at the most-retarded angle. Further, an increase in the
relative rotation phase indicates that the relative rotation phase
is advanced. In addition, a decrease in the relative rotation phase
indicates that the relative rotation phase is retarded.
[0040] The startup processing is started when the driver of the
vehicle performs a starting operation of the internal combustion
engine 500. FIG. 6 shows that the previous operation of the
internal combustion engine 500 was stopped at time te. Then later
at time t0, the starting operation of the internal combustion
engine 500 by the driver is detected, and at this time, the startup
processing begins. In the first embodiment, the controller 11 is
configured to control the relative rotation phase to the
most-retarded angle when the internal combustion engine 500 is
stopped. As a result, at time t0, the relative rotation phase is at
the most-retarded angle. It should be noted that in alternative
embodiments, the relative rotation phase when the operation of the
internal combustion engine 500 is stopped and when the startup
processing is started is not necessarily limited to being at the
most-retarded angle.
[0041] In step S10, the controller 11 detects the current
temperature of the valve timing adjustment device 10 using the
temperature detection unit 540. It should be noted that the
detected temperature of the temperature detection unit 540 can be
interpreted as representing the temperature of the lubricating oil
in the valve timing adjustment device 10 at this time. In step S20,
the controller 11 determines whether or not the temperature
detected by the temperature detection unit 540 is equal to or less
than a predetermined threshold value. In the first embodiment, the
threshold is defined as a determination condition for determining
whether or not a cold start is being executed. The threshold value
may be, for example, the current outside air temperature or an
average outside air temperature during cold weather. When the
detected temperature is equal to or lower than the threshold value,
the controller 11 executes a startup preparation control in step
S30, and when the detected temperature is higher than the threshold
value, the controller 11 skips the startup preparation control in
step S30.
[0042] The startup preparation control is performed so that the
valve timing adjustment device 10 can start operating smoothly. In
particular, during the startup preparation control, the phase
adjustment unit 15 is operated before the internal combustion
engine 500 is started in order to execute a control for changing
the relative rotation phase. Here, "control for changing the
relative rotation phase" means a control process that causes the
driven rotator 40 to rotate relative to the driving rotator 30 in
at least one of the advance angle direction and the retard angle
direction. In other words, "control for changing the relative
rotation phase" refers to a control process that causes the
rotators inside the phase adjustment unit 15 to rotate relative to
each other. The startup preparation control of the first embodiment
is executed before the cranking operation of the internal
combustion engine 500 is started. When the rotators in the phase
adjustment unit 15 are rotated during the startup preparation
control, the lubricating oil in the phase adjustment unit 15 is
discharged to an extent. During a cold start, this lubricating oil
tends to be low in temperature and high in viscosity resistance. As
a result of the discharging effect, the viscosity resistance inside
the phase adjustment unit 15 may be reduced, and the subsequent
operation of the phase adjustment unit 15 can be smoothly
performed. The startup preparation control can be interpreted as an
oil discharge control that causes lubricating oil to be discharged
from the phase adjustment unit 15.
[0043] In FIG. 6, the startup preparation control is executed
during the period from time t1 to time t2. In the startup
preparation control of the first embodiment, the controller 11
alternately performs an advance angle operation that causes the
actuator 12 to rotate forward at a high speed to advance the
relative rotation phase, and a retard angle operation that causes
the actuator 12 to rotate at a low speed or rotate in reverse. In
the first embodiment, the controller 11 repeatedly performs the
above described advance angle operation and retard angle operation,
in this order, i.e., alternately. In the example of FIG. 6, the
controller 11 repeatedly controls the relative rotation angle to
change from the most-retarded angle to an advanced angle, and then
to return to the most-retarded angle. In this regard, by performing
both the advance angle operation and the retard angle operation,
the lubricating oil can be more effectively discharged as compared
to the case of performing only the advance angle operation or
performing only the retard angle operation. As a result, it is
possible to reduce the likelihood of the lubricating oil stagnating
within the phase adjustment unit 15. Further, the advance angle
operation and the retard angle operation are alternately performed
a plurality of times, so that the lubricating oil in the phase
adjustment unit 15 can be discharged more effectively.
[0044] Referring to FIG. 3, in the first embodiment, as described
above, the speed reduction mechanism 50 is a planetary gear
mechanism including the planetary gear 52. In this case, the
startup preparation control preferably further includes controlling
the planetary gear 52 to perform at least one full revolution. That
is, the startup preparation control preferably further includes
controlling the eccentric shaft center BX to make a full revolution
around the rotation axis AX. If this is done, the lubricating oil
in the speed reduction mechanism 50 may also be discharged
effectively. Specifically, lubricating oil tends to build up in
spaces SP formed between the teeth of the planetary gear 52 and the
teeth of the driving rotator 30 and the driven rotator 40. See FIG.
3 for an example of a space SP that forms when these teeth are not
meshed with each other. When the planetary gear 52 is controlled to
make a full revolution, the lubricating oil in these spaces SP may
be effectively forced out. As a result, the viscosity resistance in
the speed reduction mechanism 50 can be effectively reduced. In the
startup preparation control of the first embodiment, in order to
ensure that lubricating oil in the spaces SP is discharged, the
planetary gear 52 is controlled to make two full rotations.
Specifically, as shown by the arrows R1, R2 in FIG. 3, the
planetary gear 52 is controlled to make one full revolution towards
the advance side, and then make one full revolution to the retard
side.
[0045] It should be noted that the startup preparation control is
not limited to a configuration in which the advance angle operation
and the retard angle operation as described above are alternately
repeated a plurality of times. In alternative embodiments, the
startup preparation control include performing the advance angle
operation and the retard angle operation only once each, or may
include performing only the advance angle operation. Further
alternatively, in the case where the relative rotation phase at the
start of execution of the startup processing of the internal
combustion engine 500 is not the most-retarded angle, the advance
angle operation and the retard angle operation may be executed
alternately in the reverse order, or only the retard angle
operation may be performed. In other words, as long as either the
advance angle operation or the retard angle operation is performed
at least once, the lubricating oil can be discharged to some
extent. In the startup preparation control, the amount advanced by
the advance angle operation and the amount retarded by the retard
angle operation may be different from each other as well.
[0046] Next, referring back to FIGS. 5 and 6, after executing the
startup preparation control in step S30, ECU 550 starts a cranking
operation in order to start operation of internal combustion engine
500. Specifically, ECU 550 drives a starter motor 525 provided in
internal combustion engine 500 and starts rotation of crankshaft
520 using the driving force from the starter motor 525. In FIG. 6,
the cranking operation is started at time t3. In the first
embodiment, prior to the start of the cranking operation, a
predetermined relative rotation phase for starting the cranking
operation is set by the startup preparation control. In the first
embodiment, the relative rotation phase for starting the cranking
operation is the most-retarded angle. If the relative rotation
phase is set to the most-retarded angle at the start of the
cranking operation, the load on the starter motor 525 from the
valve timing adjustment device 10 is minimized. As a result, the
cranking operation may be smoothly started. It should be noted that
the relative rotation phase at the time of starting the cranking
operation is not limited to the most-retarded angle, and may be set
to another phase angle in alternative embodiments.
[0047] After the cranking operation is started, the controller 11
executes a startup phase control in which the relative rotation
phase is set to an initial phase IP in step S40. In the first
embodiment, the startup phase control changes the rotation phase,
which was previously set at the time of starting the cranking
operation, to the initial phase IP. The initial phase IP is
determined in advance, e.g., experimentally, so that the operation
start of the internal combustion engine 500 can be smoothly
executed. The controller 11 executes the startup phase control in
step S40 after a predetermined time has elapsed after the start of
the cranking operation. In the first embodiment, the initial phase
IP is defined as a phase that provides an appropriate compression
ratio when the first combustion occurs in the internal combustion
engine 500. Therefore, the controller 11 performs the startup phase
control in step S40 before the first combustion occurs. The
controller 11 may, for example, execute the startup phase control
in step S40 when one compression operation is performed in the
internal combustion engine 500 during cranking operation. In an
alternative embodiment, the controller 11 may perform the startup
phase control after the first combustion of the internal combustion
engine 500 by calculating an appropriate initial phase IP based on
that first combustion.
[0048] In FIG. 6, execution of the startup phase control is started
at time t4, and the initial phase IP is set by the controller 11 as
a command value for the relative rotation phase with respect to the
phase adjustment unit 15. Thereafter, the relative rotation phase
reaches the initial phase IP at time t5, and the first combustion
occurs in the internal combustion engine 500 at time t6. At this
time, the operation of the internal combustion engine 500 is
started. In the example of FIG. 6, since the startup preparation
control is executed from time t1 to time t2, the viscosity
resistance inside the phase adjustment unit 15 is reduced at time
t4 when the startup phase control is started. As a result, the time
period from the time t4 to the time t5, which is the period when
the relative rotation phase is set to the initial phase IP, is
shortened compared to the case where the startup preparation
control is not executed, and energy consumed in that period is
reduced.
[0049] To more clearly understand the advantages and technical
effects of the embodiments described in this disclosure, a
comparison can be made with a comparative example valve timing
adjustment device. In particular, consider a comparative device
where, when an internal combustion engine is cold-started, the
lubricating oil inside a comparative valve timing adjustment device
is heated through self-heating by energizing the electromagnetic
coil of the drive motor of the comparative valve timing adjustment
device. With this configuration, if the drive motor is a brushless
DC motor, the drive motor and the gear portion are only connected
by a torque transmission component. In such a configuration, even
if the electromagnetic coil of the drive motor is heated, it may be
difficult to sufficiently transmit the heat to the lubricating oil
in the gear portion.
[0050] As a result, there is a concern that operation
responsiveness may not be sufficient during a cold start due to an
increase in viscosity resistance caused by lubricating oil in the
gear portions, whose viscosity increases is low temperatures. Such
a decrease in operation responsiveness of the valve timing
adjustment device may lead to a decrease in the performance of the
internal combustion engine.
[0051] In contrast, as described above, according to the valve
timing adjustment device 10 of the first embodiment, during the
startup processing, the startup preparation control which reduces
the amount of lubricating oil in the phase adjustment unit 15 is
performed before the startup phase control for facilitating the
start of the operation of the internal combustion engine 500.
Therefore, when the operation of the internal combustion engine 500
is started, the viscosity resistance in the phase adjustment unit
15 may be reduced, especially during cold starts. As a result, the
operation responsiveness of the valve timing adjustment device 10
may be improved.
[0052] In particular, in the valve timing adjustment device 10 of
the first embodiment, the main body 12M that is the driving force
generation source of the actuator 12 and the phase adjustment unit
15 are separated from each other. For this reason, it is not easy
to raise the temperature of the lubricating oil in the phase
adjustment unit 15 by using the driving temperature of the actuator
12. In this regard, according to the valve timing adjustment device
10 of the first embodiment, the viscosity resistance in the phase
adjustment unit 15 may be reduced due to the startup preparation
control. As a result, it is possible to effectively improve the
operation responsiveness of the valve timing adjustment device
10.
[0053] According to the valve timing adjustment device 10 of the
first embodiment, the startup preparation control is executed in a
period after a command to start the internal combustion engine 500
is received and before the cranking operation of the internal
combustion engine 500 is started. As a result, during the startup
period of the internal combustion engine 500, this time period
prior to the cranking operation can be effectively utilized.
[0054] According to the valve timing adjustment device 10 of the
first embodiment, the startup preparation control is executed when
the temperature detected by the temperature detection unit 540 is
lower than a predetermined threshold value. Therefore, the startup
preparation control can be effectively executed when the viscosity
resistance of the lubricating oil is expected to be relatively
high. When the detected temperature is high and the viscosity
resistance of the lubricating oil in the phase adjustment unit 15
is expected to be relatively low, the startup preparation control
may be skipped. As a result, the start time of the internal
combustion engine 500 is not increased due to unnecessarily
performing the startup preparation control.
[0055] The startup preparation control of the first embodiment
includes both an advance angle operation for advancing the relative
rotation phase and a retard angle operation for retarding the
relative rotation phase. Therefore, the lubricating oil can be more
effectively discharged as compared to when only one of these
operations is performed. Further, in the startup preparation
control of the first embodiment, since the advance angle operation
and the retard angle operation are alternately repeated a plurality
of times, the lubricating oil can be discharged from the phase
adjustment unit 15 more effectively. In addition, since the startup
preparation control of the first embodiment includes an operation
of rotating the planetary gear 52 for at least one revolution, the
lubricating oil present in the spaces SP between the planetary gear
52 and the driving rotator 30 and the driven rotator 40 can be
effectively discharged.
2. Second Embodiment
[0056] With reference to the flowchart of FIG. 7 and the timing
chart of FIG. 8, the flow of a startup processing performed by the
valve timing adjustment device of a second embodiment will be
described. The configuration of the valve timing adjustment device
of the second embodiment is substantially the same as the
configuration of the valve timing adjustment device 10 of the first
embodiment. The startup processing of the second embodiment is
different in that the startup preparation control is executed
during the cranking operation of the internal combustion engine
500, not before the start of the cranking operation. Other aspects
of the second embodiment are substantially similar to those of the
first embodiment.
[0057] In the startup processing of the second embodiment, the
controller 11 starts the cranking operation when the detected
temperature is equal to or lower than the threshold value in step
S20. Then, while the cranking operation is being performed, the
startup preparation control in step S30 is executed at a
predetermined timing. After executing the startup preparation
control, the controller 11 executes the startup phase control in
which the relative rotation phase is set to the initial phase IP in
step S40.
[0058] In the example of FIG. 8, after a starting operation from
the driver is detected at time t0, the cranking operation is
started at time t1, the startup preparation control is executed
from time t2 to t3, and the startup phase control is executed from
time t4 to t5. Control is being executed. In this example, during
the startup preparation control, an advance angle operation for
advancing the relative rotation phase from the most-retarded angle
is performed only once. However, this is not intended to be
limiting, and during the startup preparation control, the advance
angle operation and the retard angle operation may be performed at
least once instead, or the advance angle operation and the retard
angle operation may be alternately repeated a plurality of times as
in the first embodiment. In addition, the relative rotation phase
at the start of execution of the startup processing may not be the
most-retarded angle as well. In this case, during the startup
preparation control, only the retard angle operation may be
executed, or the retard angle operation and the advance angle
operation may be executed in this order.
[0059] According to the valve timing adjustment apparatus of the
second embodiment, after a start command for the internal
combustion engine 500 is received, the startup preparation control
is executed during the cranking operation. Therefore, the cranking
operation and the startup preparation control can be executed in
parallel, which is efficient. In addition, according to the valve
timing adjustment device and the control method thereof of the
second embodiment, various functions and effects similar to those
described in the first embodiment can be achieved.
3. Third embodiment
[0060] With reference to the flowchart of FIG. 9 and the timing
chart of FIG. 10, the flow of a stop processing performed by the
valve timing adjustment device of a third embodiment will be
described. The configuration of the valve timing adjustment device
of the third embodiment is substantially the same as the
configuration of the valve timing adjustment device 10 of the first
embodiment. In the valve timing adjustment device of the third
embodiment, the controller 11 executes the stop processing of FIG.
9 when the operation of the internal combustion engine 500 is
stopped. As will be described below, in the valve timing adjustment
device of the third embodiment, the startup preparation control is
executed during the stop processing. As such, the startup
preparation control may be omitted when starting the operation of
the internal combustion engine 500.
[0061] In step S100, the controller 11 causes the phase adjustment
unit 15 to set the relative rotation phase to a predetermined
stopping phase. Next, when the operation of the internal combustion
engine 500 is stopped, the controller 11 executes startup
preparation control for changing the relative rotation phase in
step S110 in preparation for the next startup of the internal
combustion engine 500. Additionally, in alternative embodiments,
the process of step S100 for controlling the relative rotation
phase to the stopping phase may be performed after the startup
preparation control instead.
[0062] In the example of FIG. 10, an operation by the driver that
commands the operation of the internal combustion engine 500 to
stop is detected at time t0. Then, the relative rotation phase is
set to the stopping phase at time t1. After that, the operation of
the internal combustion engine 500 is stopped at time t2. In this
example, the stopping phase is the most-retarded angle. In the
subsequent period from time t3 to t4, the startup preparation
control is executed. The startup preparation control of the third
embodiment is executed in the same manner as described in the first
embodiment.
[0063] According to the valve timing device of the third
embodiment, when the operation of the internal combustion engine
500 is stopped, the temperature of the lubricating oil is still
relatively high due to the prior operation of the internal
combustion engine 500. Therefore, at this time, the viscosity
resistance inside the phase adjustment unit 15 is expected to be
relatively low. The startup preparation control is executed in this
state. As a result, the lubricating oil can be efficiently
discharged from the phase adjustment unit 15 by the startup
preparation control. Thus, when the internal combustion engine 500
is subsequently started up at a later time, the amount of
lubricating oil inside the phase adjustment unit 15 is reduced and
the viscosity resistance inside the phase adjustment unit 15 is
reduced. Further, since the startup preparation control can be
omitted when the internal combustion engine 500 is started, the
amount of time required to start the internal combustion engine 500
can be reduced. In addition, according to the valve timing
adjustment device and the control method thereof of the third
embodiment, various functions and effects similar to those
described in the first embodiment can be achieved.
4. Fourth Embodiment
[0064] The structure of a valve timing adjustment device 10A of a
fourth embodiment will be described with reference to FIG. 11, FIG.
12, and FIG. 13. Aside from the differences described below, the
configuration of the valve timing adjustment device 10A of the
fourth embodiment is substantially the same as the configuration of
the valve timing adjustment device 10 of the first embodiment. In
FIGS. 11 to 13, components having the same reference numerals as
those described in the first embodiment have the same functions as
those described in the first embodiment even if the illustrated
shapes are different.
[0065] Referring to FIG. 11, the valve timing adjustment device 10A
includes a phase adjustment unit 15A of the fourth embodiment
instead of the phase adjustment unit 15 described in the first
embodiment. Further, the valve timing adjustment device 10A
includes an actuator 12A that is disposed inside the phase
adjustment unit 15A and integrated with the phase adjustment unit
15A, instead of the actuator 12 of the first embodiment.
[0066] The actuator 12A is formed by a brushed DC motor. The
actuator 12A includes a housing 101 which is a yoke that rotates
integrally with the sprocket 35, a motor output shaft 102 that is
rotatably provided inside the housing 101, a pair of permanent
magnets 103 fixed to the inner peripheral surface of the housing
101, a stator 104 which is a fixed member, and a brush 105a. The
permanent magnets 103 have a semicircular arc shape.
[0067] The motor output shaft 102 has a cylindrical shape. A rotor
RT is fixed to the outer surface of the motor output shaft 102. In
addition, an electromagnetic coil CL is wound around the rotor RT.
The rotation axis of the motor output shaft 102 coincides with the
rotation axis AX of the camshaft 510. The cylinder of the motor
output shaft 102 accommodates a center bolt CB fastened to the
camshaft 510. The motor output shaft 102 is rotatably supported by
a bearing 110 and a needle bearing 112 provided on the outer
periphery of the center bolt CB. In the fourth embodiment, the
motor output shaft 102 is integrated with the input rotator 20 of
the phase adjustment unit 15.
[0068] Next, referring to FIGS. 11 and 12, an eccentric shaft
portion 106 is integrally provided at the end portion of the motor
output shaft 102 facing the camshaft 510. The eccentric shaft
portion 106 is a cylindrical eccentric rotator that forms a part of
a speed reduction mechanism 50A. As shown in FIG. 11, the eccentric
shaft portion 106 is formed in a cylindrical shape. The axial
center of the eccentric shaft portion 106 is an eccentric axial
center BX, which is slightly offset from the rotation axis AX in
the radial direction as shown in FIGS. 11 and 12.
[0069] Referring to FIG. 11, in the valve timing adjustment device
10A, the driving rotator 30 with the sprocket 35 is supported by
the camshaft 510. Specifically, the driving rotator 30 is rotatable
relative to the camshaft 510 via a bearing 113 provided on the
outer periphery of the camshaft 510.
[0070] Referring to FIG. 13, a stopper groove 511 is provided on
the outer peripheral surface of the camshaft 510. The stopper
groove 511 is formed in an arc shape with a predetermined length
along the rotation direction of the camshaft 510. The length of the
stopper groove 511 defines the most-retarded angle and the
most-advanced angle of the relative rotation phase between the
driving rotator 30 and the driven rotator 40. In the valve timing
adjustment device 10A, when the engaging portion 36, which is a
protrusion provided on the inner peripheral surface of the driving
rotator 30, abuts against either end portion of the stopper groove
511, the relative rotation phase is at the most-retarded angle or
the most-advanced angle.
[0071] The valve timing adjustment device 10A includes the speed
reduction mechanism 50A instead of the speed reduction mechanism 50
described in the first embodiment. In particular, the speed
reduction mechanism 50A is a roller mechanism having a plurality of
rollers 120, instead of being a planetary gear mechanism as in the
first embodiment.
[0072] The structure of the speed reduction mechanism 50A will be
described with reference to FIG. 12. In the valve timing adjustment
device 10A, the center bolt CB passes through the center of the
driven rotator 40. The needle bearing 112 that supports the input
rotator 20 described above is provided on the outer periphery of
the driven rotator 40. The needle bearing 112 supports the
eccentric shaft portion 106 of the input rotator 20. A ball bearing
115 is provided on the outer periphery of the eccentric shaft
portion 106. On the outer periphery of the ball bearing 115, the
plurality of rollers 120 constituting the speed reduction mechanism
50A are arranged at equal intervals over the entire circumference.
Each roller 120 is interposed between a plurality of retainers 121
provided integrally with the driven rotator 40. The rollers 120 are
retained in a state in which movement in the radial direction is
permitted. Each roller 120 faces the inner peripheral surface of
the driving rotator 30. Recesses 39 are formed over the entire
circumference on the inner circumferential surface of the driving
rotator 30. The rollers 120 can be partially fit inside the
recesses 39.
[0073] The ball bearing 115 is disposed so as to be substantially
overlapping in the radial position with the needle bearing 112. The
rollers 120 are constantly in contact with the outer peripheral
surface of the ball bearing 115. As shown in FIG. 12, a crescent
shaped gap is formed on the outer peripheral side of the ball
bearing 115. This crescent shaped gap allows the entire ball
bearing 115 to move in the radial direction in accordance with the
eccentric rotation of the eccentric shaft portion 106. In other
words, the ball bearing 115 is capable of eccentric movement. In
this regard, in the speed reduction mechanism 50A, the ball bearing
115 and the eccentric shaft portion 106 are collectively referred
to as an eccentric rotator. Further, in accordance with the
eccentric movement of the ball bearing 115, the rollers 120 are
moved back and forth in the radial direction while being guided by
the retainers 121.
[0074] In the valve timing adjustment device 10A, the eccentric
shaft portion 106 rotates eccentrically in accordance with the
rotation of the motor output shaft 102. When this happens, the
rollers 120 are guided by the retainers 121 during each rotation of
the motor output shaft 102. Specifically, as the motor output shaft
102 rotates, each roller 120 is guided to roll over each recess 39
of the driving rotator 30 and roll into an adjacent recess 39. the
driving rotator 30 and rolls to another adjacent recess 39 while
moving along the circumferential direction. The rotation speed of
the motor output shaft 102 is reduced by the movement of each
roller 120, and this rotational force is transmitted to the
camshaft 510 via the driven rotator 40.
[0075] In the valve timing adjustment device 10A, the relative
rotation phase between the crankshaft 520 and the camshaft 510 is
controlled by forward and reverse rotation control of the motor
output shaft 102 by the controller 11. When the driven rotator 40
rotates in the same direction as the rotation direction of the
driving rotator 30, the relative rotation phase is changed to the
advance side. Conversely, when the driven rotator 40 rotates in the
opposite direction as the rotation direction of the driving rotator
30, the relative rotation phase is changed to the retard side.
[0076] In the valve timing adjustment device 10A of the fourth
embodiment as well, the controller ibis configured to reduce the
amount of lubricating oil inside the phase adjustment unit 15 when
the internal combustion engine 500 is started by performing the
startup processing including the startup preparation control, as
described in the first embodiment. As a result, when the operation
of the internal combustion engine 500 is started, the viscosity
resistance in the phase adjustment unit 15 may be reduced,
especially during cold starts. As a result, the operation
responsiveness of the valve timing adjustment device 10A may be
improved. In the startup preparation control of the valve timing
adjustment device 10A, the retard angle operation and the advance
angle operation are preferably performed so that the eccentric axis
BX makes at least one full revolution around the rotation axis AX.
As a result of doing this, the lubricating oil can be discharged
from the crescent shaped gap on the outer peripheral side of the
ball bearing 115, and the viscosity resistance in the speed
reduction mechanism 50A can be effectively reduced. In addition,
according to the valve timing adjustment device 10A and the control
method thereof of the fourth embodiment, various functions and
effects similar to those described in the first embodiment can be
achieved.
5. Other Embodiments
[0077] The various configurations described in the above
embodiments can be modified as follows, for example. The various
embodiments described below are intended to be exemplary
implementations of the technology described in this disclosure,
similar to the embodiments described above.
Modified Embodiment 1
[0078] In the startup processing of each of the above embodiments,
the processes of steps S10 and S20 may be omitted. In other words,
the controller 11 may execute the startup preparation control in
the startup processing regardless of the temperature of the valve
timing adjustment devices 10 and 10A.
Modified Embodiment 2
[0079] In the startup processing, the controller 11 may execute the
startup preparation control both before the start of the crank
operation and during the execution of the crank operation. Further,
the controller 11 may execute the startup preparation control while
the internal combustion engine 500 is stopped as well. For example,
when the internal combustion engine 500 is stopped, the controller
11 may periodically start up, check the outside air temperature.
Then when the controller 11 detects that the outside air
temperature has dropped below the predetermined threshold value,
the controller 11 may perform the startup preparation control in
anticipation of the next time that the internal combustion engine
500 is started.
Modified Embodiment 3
[0080] In the valve timing adjustment device 10A of the fourth
embodiment, the startup processing described in the second
embodiment and the stop processing described in the third
embodiment may be performed instead of the startup processing
described in the first embodiment. In this case, according to the
valve timing adjustment device 10A of the fourth embodiment, the
various functions and effects similar to those described in the
second and third embodiments can be achieved as well.
Modified Embodiment 4
[0081] In each of the embodiments described above, the phase
adjustment units 15 and 15A are not necessarily filled with
lubricating oil after operation is stopped. Even in this case, if
the phase adjustment units 15 and 15A are driven by the startup
preparation control, performance of starting the internal
combustion engine 500 may nevertheless be improved due to, for
example, reducing sticking between the rotators in the phase
adjustment units 15 and 15A. Therefore, it is possible improve the
operation responsiveness of the valve timing adjustment devices 10
and 10A.
Modified Embodiment 5
[0082] In each of the embodiments described above, the speed
reduction mechanisms 50 and 50A may be other types of planetary
gear mechanisms, or may be other types of roller speed reduction
mechanisms.
6. Other Modifications
[0083] The technology of the present disclosure is not limited to
valve timing adjustment devices, and can be implemented in various
forms aside from valve timing adjustment devices. The technology of
the present disclosure may be applied to, for example, a control
device or control method of a valve timing adjustment device, an
internal combustion engine system including the valve timing
adjustment device, a vehicle including the internal combustion
engine, a starting method of the internal combustion engine, a
stopping method of the internal combustion engine, and so on. In
addition, the technology described herein can be implemented in the
form of a computer program for executing the above described
control method, a storage medium on which this computer program is
recorded, and so on.
[0084] The technology of the present disclosure should not be
limited to the embodiments described above or the modifications
described above, and various other embodiments may be implemented
without departing from the scope of the present disclosure. For
example, the technical features in the embodiments can be replaced
or combined as appropriate. In addition, any technical features
which are not explicitly described as being essential may be
omitted where appropriate.
* * * * *